ALK and non-small cell lung carcinoma: Here, we compare the efficacy of crizotinib, pemetrexed and other chemotherapy regimens as a first line treatment of Chinese patients with ALK-positive NSCLC and evaluate the impact of first line therapy (pemetrexed or not-pemetrexed), brain metastasis (BM) before crizotinib treatment, ECOG score etc. on the PFS of crizotinib treatment by the Kaplan–Meier survival analysis and Cox proportional hazards model in a real world.